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      <title>Zookeeper做为注册中心，主要存储哪些数据？存储在哪里？ - 交互式测验</title>
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    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>Zookeeper做为注册中心，主要存储哪些数据？存储在哪里？ - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
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                    <div id="hint-container" class="hint-container"></div>
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                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
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      <script>
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  {
    "question": "当一个服务消费者需要实时获取服务提供者列表的更新（例如新实例上线或下线）时，Zookeeper 提供了哪种核心机制来实现这一功能？",
    "options": [
      "通过直接读取 Zookeeper 的本地数据快照文件。",
      "通过订阅（watch）服务目录下的节点变化，利用事件通知机制。",
      "通过轮询 Zookeeper 的 HTTP API 来定期查询服务列表。",
      "通过执行 SQL 查询 Zookeeper 内部的元数据数据库。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "Zookeeper 的核心机制之一是 Watcher（监视器）。服务消费者可以对某个 ZNode（目录节点）设置一个 Watcher，当该节点或其子节点发生变化（如新增、删除）时，Zookeeper 会主动向客户端发送事件通知，从而让消费者能够实时感知服务实例的变化，而无需低效地轮询。",
    "source": "文档中「2. 服务发现信息」部分",
    "hint": "服务消费者如何“订阅”服务目录的变化以获取最新状态？"
  },
  {
    "question": "Zookeeper 使用哪两种特殊的节点类型来实现分布式锁和选举等协调机制？",
    "options": [
      "配置节点和数据快照节点。",
      "临时节点（ephemeral nodes）和顺序节点（sequential nodes）。",
      "持久节点（persistent nodes）和健康检查节点。",
      "主节点（master nodes）和从节点（slave nodes）。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "临时节点在客户端会话结束后会自动删除，这一特性非常适合用于实现锁的自动释放和故障检测。顺序节点则可以在节点名后自动附加一个递增的序号，这对于实现公平锁和分布式队列至关重要。这两种节点的组合是 Zookeeper 实现复杂分布式协调功能的基础。",
    "source": "文档中「5. 分布式锁和协调数据」部分",
    "hint": "思考一下，哪种节点类型可以在客户端断开连接时自动删除，从而巧妙地实现锁的释放？"
  },
  {
    "question": "关于 Zookeeper 的数据持久化方式，以下描述哪项是正确的？",
    "options": [
      "数据被存储在外部的关系型数据库（如 MySQL）中以保证事务性。",
      "数据完全存储在内存中，不进行持久化以追求极致性能。",
      "数据存储在本地文件系统，由数据快照（snapshots）和事务日志（transaction logs）组成。",
      "数据以单一的大文件形式存储在共享网络文件系统（NFS）上。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Zookeeper 确保数据的持久性和可靠性，通过将其存储在本地文件系统中。它使用两种文件类型：数据快照（snapshot），用于记录某一时刻的全量数据状态；事务日志（log），用于记录所有的数据变更操作。这种设计确保了在节点重启或故障恢复时可以恢复到最新状态。",
    "source": "文档中「存储位置」部分",
    "hint": "Zookeeper 使用哪两种文件来记录其数据状态和变更历史，以确保数据不会丢失？"
  },
  {
    "question": "Zookeeper 是如何判断一个服务实例是否已经不可用的？",
    "options": [
      "如果服务实例在预定时间内未能更新其在 Zookeeper 中的节点信息（如心跳），则认为其不可用。",
      "服务实例在下线前必须向 Zookeeper 发送一个明确的“下线”指令。",
      "Zookeeper 主动向服务实例发送 ping 请求，如果超时则认为其不可用。",
      "依赖于底层的 TCP 连接状态，如果 TCP 连接断开则认为服务不可用。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "服务实例通过定期更新其在 Zookeeper 中对应的节点（通常是临时节点）来报告其“存活”状态，这通常被称为心跳机制。如果 Zookeeper 在一定时间内没有接收到某个节点的更新或心跳，它就会假定该服务实例发生故障或已下线，并通知所有订阅了该服务的消费者。",
    "source": "文档中「4. 服务健康状态」部分",
    "hint": "服务实例如何向 Zookeeper 证明自己“还活着”？"
  },
  {
    "question": "在 Zookeeper 中，服务注册信息、配置数据等是如何被逻辑组织的？",
    "options": [
      "以关系型数据库的表（Table）结构进行组织，通过行和列存储数据。",
      "以简单的键值对（Key-Value）列表形式存储，所有数据都在同一层级。",
      "以图形数据库的模式，通过节点和边的关系来组织。",
      "以类似文件系统的树状目录结构进行组织，每个服务或配置项对应一个节点（node）。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "Zookeeper 内部的数据模型是一个层次化的命名空间，非常类似于一个标准的文件系统。每个节点（称为 ZNode）都可以存储数据，并且可以拥有子节点。这种树状结构使得数据的组织和分类非常清晰和灵活，例如可以按 /services/service-name/instance-id 的路径来组织服务实例。",
    "source": "文档中「1. 服务注册信息」部分的“存储方式”",
    "hint": "Zookeeper 的存储结构常被比作哪种常见的操作系统组件？"
  },
  {
    "question": "在一个 Zookeeper 集群中，如何确保所有节点的数据最终保持一致？",
    "options": [
      "通过两阶段提交（2PC）协议来确保所有节点同步更新。",
      "每个节点独立写入，然后通过后台任务定期进行数据同步和冲突解决。",
      "通过使用复制协议（如 Zab 协议）将数据变更操作复制到集群中的多个节点。",
      "依赖于一个中心化的主节点，所有读写操作都必须经过该节点处理。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "为了保证高可用和数据一致性，Zookeeper 采用集群模式部署。集群内部使用一种原子广播协议（文档中提到的 Zab 协议是其实现）来确保所有写操作的顺序和结果在整个集群中是一致的。一个写请求会先被 leader 节点处理，然后广播给所有 follower 节点，只有当大多数节点确认写入成功后，该操作才被视为提交成功。",
    "source": "文档中「存储位置」部分的“数据持久化”",
    "hint": "文档提到了一个特定的复制协议来保证集群中节点的数据一致性，它是什么？"
  }
];
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          optionsListEl.innerHTML = '';
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            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

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                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
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            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  